The present invention relates to the field of electric conductor inspection. In particular, the invention relates to a self-contained apparatus for inspecting energized and de-energized conductors.
Utility companies have long sought to reap the benefits of early detection of overhead power line/conductor defects. Identifying conductor issues early can facilitate the maintenance and replacement decision making process and prioritize repairs that should be made. Correctly separating troubled conductors from those with additional life can help companies avoid expensive maintenance work, line-drops, failures, and regional outages.
A number of methods and technologies have been used to detect damaged or aged transmission conductors. These include visual inspection, infrared thermography, and overhead line corrosion detection (OHLCD).
The traditional method for detecting damage to an overhead transmission conductor has required power company line personnel to disassemble and remove tower hardware and armor rods and open up the conductor for visual inspection. This “hands on” method of inspection requires the conductor to be de-energized in most cases. Further, line personnel are only able to detect damage to the outer strands of the conductor and cannot see critical sub-surface damage.
OHLCD technology uses a trolley unit that contains both a corrosion detector and a data telemetry system. The unit is attached to the conductor in question and towed along the conductor by a second lightweight, motorized radio-controlled trolley. While this technology is able to detect corrosion in the conductor core, it does not look at the effects of corrosion on the outer conductor strands. Also, the unit is not capable of testing areas under suspension clamps unless they are removed, thus, requiring the conductor to be de-energized. Further, OHLCD technology does not detect strand breaks or non-functional splice repairs.
Infrared thermography and X-ray techniques have improved the ability of utility companies to detect issues with substation and tower hardware. However, these techniques have been less successful at the detection of flaws in overhead transmission conductors. Infrared or X-ray surveys of transmission conductors require an airplane and other expensive equipment. The costs of such services and the limited results they yield have yet to demonstrate a real cost-benefit justification.
The high-cost and time-intensive nature of the methods described above coupled with tight operational and maintenance budgets have resulted in infrequent conductor inspection and a growing risk of failure that is neither quantified nor fully understood. As a result, companies are forced to make decisions regarding the replacement of power transmission conductors without proper diagnosis tools. These decisions often result in the replacement of conductors with remaining life and the non-replacement of conductors near failure, thereby resulting in substantial costs per year for unneeded replacements. Armed with solid information about the relative condition of various transmission conductors, utility personnel can make more effective operational and maintenance decisions that save the company substantial amounts of both time and money.
Accordingly, there is a need for a self-contained apparatus that allows companies to test conductors accurately and efficiently for corrosion, poorly installed splices, and broken strands of the conductors without de-energizing the conductors or disassembling hardware.